1. Field of Invention
This invention relates to a relay busbar device with a built-in current sensor for vehicles, which forms a power circuit between a traction motor and an inverter in a vehicle equipped with the motor such as an electric vehicle (EV), fuel cell vehicle (FCV), hybrid vehicle (HV), and plug-in hybrid vehicle (PHV, PHEV), and which incorporates therein a sensor to detect the current flowing in the power circuit.
2. Related Background Art
Among vehicles equipped with this type of traction motor (hereafter “motor”), the power terminals of motors (including motor-generators) and generators and the inverter power terminals of power control units (PCUs) are connected using a relay busbar, and a power circuit (current path) is thereby formed between the motor or similar and the inverter; power is supplied from a battery to the motor via the PCU using the current path (relay busbar), and generated power is supplied from the generator via the inverter (PCU) to the battery using the current path. At this time, a current sensor is attached to the relay busbar, and this current sensor is used to measure the current flowing in the relay busbar; and feedback power (current) control is performed based on comparison of that measured value with a current instruction value, and the motor is controlled at the desired revolution rate and torque in the PCU.
The current sensor normally comprises a ring-shape magnetic core with a portion removed, such as a U-shape core or similar, surrounding the relay busbar, and a magnetic sensor provided in the core removed portion (gap); the magnetic flux occurring in the removed portion due to current flowing from the inverter to the motor via the relay busbar is detected by the magnetic sensor, and the detected value (measured value) is sent to the PCU. This current sensor is attached to the relay busbar, and so is built into the relay busbar device.
Such a power circuit between the motor (including a motor-generator or generator; similarly below) and the inverter has conventionally been formed using a wire harness (cables); positioning the wire harness requires positioning space, and the need for the positioning process has been a cause of increased costs.
Hence connector structures have been suggested which form the power circuit, and in which a relay busbar device with a built-in current sensor for a vehicle, with a current sensor built into the power circuit, makes connections by fitting motor power terminals and inverter terminals into the relay busbar device (Japanese Patent Application Laid-open No. 2011-15586 and Japanese Patent Application Laid-open No. 2008-114839).
A structure has also been suggested in which a relay busbar penetrates a resin molded member, and the current sensor is built into the resin molded member (Japanese Patent Application Laid-open No. 2011-209158).